Oil well pump



W. G. GREEN OIL WELL PUMP Feb. 13, 1962 3 Sheets-Sheet 1 Filed July 23,1958 W. G. GREEN OIL WELL PUMP Feb. 13, 1962 5 Sheets-Sheet 2 F IG. 5

Filed July 25, 1958 FIG. 3

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011. WELL PUMP 3 Sheets-Sheet 3 Feb. 13, 1962 Filed July 23, 1958 kw IBY J A. 441.49.

flas/vr 3,020,848 OIL WELL PUMP William G. Green, Tulsa, Okla. (321046th Ave. N., St. Petersburg, Fla.) Filed July 23, 1958, Ser. No.750,390 1 Claim. (Cl. 103-46) This equipment relates to oil Wellproduction equipment and more particularly to a fluid pump of the freepiston type.

An object of this invention is to provide an oil pump assembly which maybe lowered into the. oil pool of a gas pressure well and which pump willlift the oil to the surface of the well with a minimum loss of gaspressure.

Another object is to provide a gas operated, oil weight controlled liftpump which operates automatically and under the well pressureconditions.

And a further object is to provide a lift pump assembly which ejects oilup a long pipe height with a controlled amount of lost gas for each oilejection.

And yet another object is to provide an oil pump which is adapted tolift oil out of a well of great depth and which operates in stages, theinitial stage being operated by the total bottom hole pressure, anotherstage being operated by the differential oil pressure, and another stagebeing operated by the gas pressure alone.

And another object is to provide an oil pump for lifting a column of oilout of a well by applying only the necessary amount of gas volume to dothe job, and then relying on the immediate loss of pressure in the wellto prevent the escape of gas after the necessary amount has beenexpended.

These and other objects and advantages will be apparent from anexamination of the following specification and drawings in which:

FIG. '1 is an outline schematic drawing of an oil well installationemploying the pump assembly of this invention.

FIG. 2A is cross sectional view of the pump assembly installed in a wellbore in its initial operating position; FIGS. 2B-2E are additional viewssimilar to FIG. 2A but shown schematically and diagrammatically inoutline form to illustrate subsequent operating positions of thisdevice.

FIG. 3 is a cross sectional drawing of the top portion of the oil welltubing shown in FIG. 1, and shown here in a horizontal position, andshowing the top section of the oil pump assembly.

FIG. 4 is the next lower portion of the well tubing and the nextsubsequent section of the pump assembly.

FIG. 5 is a drawing of the next continuous subsequent portion of thepump and tubing to that shown in FIG. 4.

FIG. 6 is the next continuous subsequent drawing of FIG. 5.

FIG. 7 is a lower continuation of FIG. 6 showing the end of the pumpassembly.

FIG. 8 is an end view looking up from the bottom of the well bore or aswould be taken along the lines 88 of FIG. 7.

Referring now more particularly to the characters of reference on thedrawing, it will be observed that the pump assembly, identifiedgenerally at 2 in FIG. 1 is installed at the lower end of a string ofproduction tubing 3 in a well bore casing 4 which is sealed at its upperend at 5 relative to the tubing 3 at approximately the ground level L.The pump assembly 2 is immersed partly in the liquid oil 0 in the wellbore and extends above the oil and into the gas zone G. At the top ofthe well bore a pressure gage 7 has been installed to check the gaspressure in the annulus between the casing 4 and tubing 3 for testpurposes. The extreme upper end of the tubing 3 States Patent 0 extendsup through the top of the sealed end 5 and is capped at 8 to seal offthe tubing and also retain a bumper spring 10, against which aconventional free piston 15 of this assembly is adapted to abut. At adistance below the bottom of the piston 15 when the latter engages thespring 10, a T 16 is installed in the tubing to connect with flow line17 through which the oil is delivered to storage tanks (not shown).

The lower end of the casing 4 may be open and extend into an oil pool Pand it is perforated as shown at 19 where the perforations connect witha gas zone Z in the formation F to form a communication with the annulusfor a restricted entry therein of the gas G.

The construction of the unique pump assembly 2 of this invention may beobserved in FIGS. 3-8 to comprise basically a body 20 having a centertube 21 which extends axially through the assembly 2 for virtually itsfull length and a concentric housing 22 which surrounds the tube 21 andis spaced therefrom by collar 23 and trun nion assembly 24. A series offixed disks 2629 divide the interior of the tube into separatecompartments and a stationary end member 31 having a divider 32 providesanother compartment by cooperation with the floating end member 34. Afitting 35 is threaded into divider 32 and is adapted to receive a valvestem 36 in sliding re lation to the fitting bushing 37 in such a mannerthat as long as the ports 38 of the channel 39 of valve stem 36 are incontact with the bushing 37, there will be no flow through the valvestem 36 by any oil 0 below the cap member 34. The main valve body 41extends through the disks 27 and 28 in sliding but fluid tight relation,and both the valve body 41 and the piston 43 operate through the disk29. The lower cap member 34 includes a ridge 45 which provides a captivefit with the end member 31 and an extension 47 thereon. An 0 ring 48provides sliding but fluid tight seal between the members 32 and 34 anda compression spring 50 with a pre-set resistance is inserted betweenthese members. The piston 43 is also held in its lowermost position by apre-set spring 51. A channel 52 extends completely through the piston 43and the upper end of this piston operates against a small spring 53 inthe upper end of bore 54, and this bore opens laterally to port 55. Theupper end of body 41 acts against a compression spring 57 which alsoseats against the fixed disk 27.

A relatively long tubing 60 extends from a point above the oil level inthe casing so as to admit gas pressure into the compartments defined bythe tube 21 at the ports 61 and 62. A second tubing 64 extends downalong and adjacent the opposite side of the center tube 21 to provide anoil passageway from the oil below and in the compartment adjacentfitting port 65 to the compartment adjacent port 66 and thence toport 67which is adjacent the output chamber 68 of the pump assembly 2 which isdirectly above the normal position of rest for free piston 15.

The main valve body 41 includes an axial gas channel 70 which extendsfrom a top opening downward to a side port 71 just above the oil port65. Ports 71 and 55 open into separate grooves 72 and 73 respectively tofacilitate discharge. The oil delivery tubing 64 includes a ball checkvalve 75 between its ports 65 and 66 to prevent unintended return of theoil to its inelt chamber The operation of the complete pump assembly 2may be observed by reference to the five stages shown at AE of FIG. 2.The first stage, FIG. 2-A shows the pump assembly 2 in its initialcondition upon being lowered into an oil pool P in a well bore. In thisposition, the free piston 15 is at rest on disk 26, and the valve body41, piston 43, and floating end member 34 are all in their lowermostposition. FIG. 2-B represents the second stage of the pump operationwhere the cup 34 has started to move the piston 43 and valve 41 upward.FIG. 2-C represents the third stage wherein the valve 41 has movedupward sufiicient to permit oil to flow through passageways in the pumpassembly into the discharge chamber 68. FIG. 2-D shows the fourth stagein this operation when the gas valve port 61 is opened throughpassageways in the pump assembly to its pressure or propulsion chamber88. The fifth stage is depicted in FIG. 2E to represent the pump just atthe point the oil is beginning to be discharged at the surface of thewell. After this event the various valves and operating parts of thepump return to their initial position as shown in FIG. 2-A and the freepiston continues upward until it is rebounded by the spring 10 (FIG. 1)and thereafter returns to its position of rest against disk 26.

When the surrounding oil has come in contact with the lower end 811 ofmember 34 and its pressure exceeds the pressure of spring 50, the member34 will move upward and valve stem 36 will pass through the bushing 37until it opens into chamber 76 and the oil then flows freely throughchannel 37 until it has built up sufficient pressure against the bottomof piston 43 to raise it upward until its enlarged section 81 abuts thelower end 82 of valve body 41 and then proceeds to raise the valve body41 upward until a detent 83 in the upper valve stem 84 engages thespring-loaded ball 85 to assume momentarily the third stage of operationas seen in FIG. 2-C. At this stage the oil port "55 is aligned withfitting port 65 and the oil coming in through the lower valve 36 is ableto pass through the pump and into tubing 64 past ball valve 75 and upthrough port 65 whereat it fills the outlet chamber 68 above pistonuntil the oil now in tubing 64 above port 66 exceeds the resistance ofspring 57, at which point the piston 86 is raised, and

being integral therewith causes the entire valve body 41 to raise untilthe second detent 87 engages the ball assembly 85. At this point the gastubing port 61 will coincide with the gas inlet port 71 and pressurizedgas will pass up through the channel 70 until the pressure in chamber 88is greater than the combined weight of the oil in outlet chamber 68 andthe weight of the piston 15 and friction resistance, whereupon the freepiston 15 rises up the tubing 3 until the oil begins to spill out intoflow line 17, whereafter the resistance of the free piston 15 on thelifting gas becomes less and the gas is permitted to expand and morerapidly push the piston 15 up and the oil out. The restricted opening ofport 71 prevents the gas from the annulus A from equalizing under thefree piston as fast as the gas is expanding in the tubing at thatlocation. When the oil has all gone out into the flow line 17, the freepiston impacts against the bumper spring 10 and the operating gas alsoescapes out through the T 16. When this expansion and reduction in gaspressure begins to take place, the pressure exerted on the oil in thetubing 64 and under piston head 86 drops off until it is no longer ableto balance the pressure of spring 57 so that the latter overcomes theresistance of the detent 87 and ball 85 and returns piston 86 and valvebody 41 to its initial position of rest against disk 29. Further downthe valve body 41, the 0 rings 88 move to seal off the gas inlet port 61so that no further gas is lost after the oil quantity is delivered. Thefact that the use of a quantity of gas from annulus A has reduced thepressure there, the lower springs 51 and 50 are now able to return thepiston 43 and end member 34 to their initial position, and ready for thenext pumping action which will occur when the formation pressure hasbuilt up the pressure in the annulus to an operational value again.

The presence of by-pass channel 89 to provide communication between theenclosed chambers 90 and 91 will prevent high resistance due tocompressing or expanding air entrapped in these chambers. Other similarchannels may be provided where desirable in this assembly.

From the foregoing description it will be readily seen that there hasbeen produced a device as substantially fulfills the objects of theinvention as set forth herein.

While this specification sets forth in detail the present and preferredconstruction of this invention, still in practice such deviations fromsuch detail may be resorted to as do not form a departure from thespirit of the invention as defined in the appended claim.

Having thus described the invention, what is claimed as new and usefuland is desired to be secured by Letters Patent is:

A pump assembly for an oil well having a pressurized gas zone, an oilzone below the gas zone and subjected to the pressure therefrom at theoil level in the well bore, comprising: a tube containing atmosphericpressure extending from the surface of the well bore down to the pumpbody, a free piston in the tube, an oil port in the tube above the freepiston, an oil passageway connecting the oil port to the pressurizedoil, a gas port in the tube below the piston, a gas passagewayconnecting the pressurized gas zone through the gas port with theunderside of the piston, a central valve in said pump body initiallyoperated by the combined oil and gas pressure to introduce oil throughthe oil passageway and into the tube, a channel from the central valveto the oil zone at the lower end of the pump body, a lower valveoperated by the combined oil and gas pressure to close the channel whenthis combined pressure is below a certain valve, means in said centralvalve operated by the weight of the oil in said first named passagewayto shut off the oil passing through said oil port and introducepressurized gas through said gas port and lift said free piston and oilthere above to the surface of the well, and means in said central valveto shut off the gas port when the pressure in said tube drops sharply,

and means to shut off said lower valve when the pressure in said gaszone drops off.

References Cited in the file of this patent UNITED STATES PATENTS1,943,522 Fletcher Jan. 16, 1934 2,013,111 Scott Sept. 3, 1935 2,246,577Davis June 24, 1941 2,508,174 Knox et al. May 16, 1950

